Fabrication of Zn-doped Cu(In, Ga)Se₂ thin film solar cells prepared by Zn diffusion from the gas phase using dimethylzinc

Cu(In, Ga)Se₂ (CIGS) solar cells were fabricated by thermal diffusion of Zn into p-type CIGS films using dimethylzinc [(CH₃) ₂Zn: DMZn] vapor, in order to form CIGS pn-homojunction. This method requires no additional processing equipment, because diffusion can be carried out subsequent to the CIGS growth. The average conversion efficiency of the CIGS solar cells consisting of n-type MgZnO transparent conducting oxide (TCO) film and n-CIGS:Zn/p-CIGS structure (4%) was improved by a factor of two in comparison with the case for undoped CIGS absorbing layer (2%). The appropriate flow time of DMZn was 3 s, from which the diffusion depth is estimated as about 150 nm. The method is highly advantageous for development of low-cost solar modules.